Well that's a long Q but here's a short A!

Your attic is not viable to grow as the enzymatic processes of cannabis start to break down at 95 degrees, and growth stops much sooner. If there is a window up there and you can add AC, then we can talk lol.... Even WITH AC running from April 1st until October, I STILL have battles with heat in my attic and occasionally lose weak plants to heat-related ailments.

As for t12 flouros, by all means!!!! I love shop lights personally. In fact Ilike them more than CFLs since they burn so cool. For flowering you will have to find something else [hps!!!!] but you can veg under a bank of 4 t12 tubes VERY nicely. Demeter's beautiful garden is a fine example of plants that were vegged under tube flouros.. but she's in the cellar and has IDEAL temps at all times. That will make all the difference in the world!!!!